System and method for sensing a paper roll ultrasonically

ABSTRACT

A system includes an ultrasonic transducer positioned to be in contact with the outer surface of a paper roll. The system further includes a transmitter circuit and a receiver circuit in communication with the ultrasonic transducer. The transmitter circuit provides a transmit signal to the ultrasonic transducer for generating an ultrasonic signal, which is transmitted into the paper roll. The receiver circuit provides a received signal indicative of an ultrasonic return echo from the paper roll. The ultrasonic return echo resulting from the ultrasonic signal interacting with the paper roll. The system also includes a processor circuit for determining an amount (length or diameter of roll) of paper remaining on the paper roll in response to the transmit signal and the receive signal. The processor provides an output signal when the amount of paper remaining falls below a threshold. A method of sensing paper on a paper roll is also presented. The method includes transmitting an ultrasonic signal into a paper roll and detecting an ultrasonic return echo from the paper roll. The ultrasonic return echo resulting from the ultrasonic signal interacting with the paper roll. The method further includes determining an amount of paper remaining on the paper roll in response to the ultrasonic return echo transmit signal.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a system and method for sensing a paper roll,and particularly to a system and method for ultrasonically sensing anamount of paper remaining on a paper roll.

2. Description of Background

Receipt printer paper, such as are commonly found with point of saledevices, usually comes in rolls. Before our invention, it has beendifficult to for a printer to estimate the amount of paper remaining ona roll. This is in part due to the various roll sizes and varieddiameters of the hollow center carriers on which the rolls are mounted.In other words, even if two rolls have the same overall outsidediameter, one may have a hollow center carrier with a greater outerdiameter, thereby resulting in less paper on that roll.

Currently, the last few feet of the paper on a roll are marked withcolored ink. When the operator of the point of sale device notices thecolored ink on the paper receipts being dispensed, they know to replacethe paper roll, as it will soon run out. This tends to worksatisfactorily for point of sale devices that are operated by a staffperson of an establishment. However, for self-service devices thatdispense receipts, the user (when seeing the colored ink on theirreceipt) does not reliably notify (if at all) a staff person that thepaper roll needs to be replaced.

SUMMARY OF THE INVENTION

The shortcomings of the prior art are overcome and additional advantagesare provided through the provision of a system sensing paper on a paperroll. The system includes an ultrasonic transducer positioned to be incontact with the outer surface of the paper roll. The ultrasonictransducer can be a piezoelectric ceramic ultrasonic transducer. Thesystem further includes a transmitter circuit in communication with theultrasonic transducer. The transmitter circuit provides a transmitsignal to the ultrasonic transducer. The ultrasonic transducer generatesan ultrasonic signal in response to the transmit signal. The ultrasonicsignal is to be transmitted into the paper roll. The system stillfurther includes a receiver circuit in communication with the ultrasonictransducer. The receiver circuit provides a received signal indicativeof an ultrasonic return echo from the paper roll. The ultrasonic returnecho resulting from the ultrasonic signal interacting with the paperroll. The system also includes a processor circuit in communication withthe transmitter circuit and the receiver circuit. The processor circuitdetermines an amount of paper remaining on the paper roll in response tothe transmit signal and the receive signal. The processor provides anoutput signal when the amount of paper remaining falls below athreshold.

A method of sensing paper on a paper roll is also presented. The methodincludes transmitting an ultrasonic signal into a paper roll anddetecting an ultrasonic return echo from the paper roll. The ultrasonicreturn echo resulting from the ultrasonic signal interacting with thepaper roll. The method further includes determining an amount of paperremaining on the paper roll in response to the ultrasonic return echotransmit signal.

System and computer program products corresponding to theabove-summarized methods are also described and claimed herein.

Additional features and advantages are realized through the techniquesof the present invention. Other embodiments and aspects of the inventionare described in detail herein and are considered a part of the claimedinvention. For a better understanding of the invention with advantagesand features, refer to the description and to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other objects, features, andadvantages of the invention are apparent from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 diagrammatically illustrates one example of a system for sensinga paper roll ultrasonically; and

FIG. 2 illustrates one example of a return echo signal plotted as afunction of amplitude and time.

The detailed description explains the preferred embodiments of theinvention, together with advantages and features, by way of example withreference to the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to the drawings in greater detail, it will be seen that inFIG. 1 there is a paper roll 10 such as is commonly found inpoint-of-sale devices for use in printing receipts, which includes acontinuous sheet of paper 30 rolled onto a hollow carrier 40. The hollowcarrier 40 is typically composed of a cardboard or plastic material.Paper roll 10, and, more particularly, the carrier 40, is typicallydisposed on a spindle 12 of a point of sale device (not shown), as iswell known. A feeder 14 of the point of sale device dispenses paperreceipts, also as is well known. An ultrasonic transducer 16 ispositioned, by a biased holder 18, to be in contact with the outersurface of the paper roll 10. The biased holder 18 is simply a holderreceptive to supporting the ultrasonic transducer 16 that is mountedwithin the point of sale device with a force applied to maintain contactof the ultrasonic transducer 16 with the outer surface of the paper roll10. The biased holder 18 further includes a pair of rollers 20 thatpermit the paper roll 10 to easily rotate relative to the ultrasonictransducer 16 while maintaining the aforementioned contact with thepaper roll 10. The ultrasonic transducer 16 can be a piezoelectricceramic ultrasonic transducer.

The ultrasonic transducer 16 is electrically connected by lines 22 to anelectronic circuit assembly 24, which is disposed within the point ofsale device. A transmitter circuit 26 provides a transmit signal to thetransducer 16 for generating an ultrasonic signal 34 to be transmittedinto the paper roll 10. A receiver circuit 28 measures a detected returnecho 36 from the transducer 16, of the ultrasonic signal. Amicroprocessor 32 is provided to process the measured return echo todetermine an estimated amount of paper remaining on the paper roll 10.Once it is determined that the paper is about to run out, an outputsignal is generated to indicate that the paper roll needs to bereplaced. The amount of paper remaining when the signal to replace thepaper roll is generated can be set at the processor 32. This outputsignal may simply activate a visual display (such a lamp, not shown),drive an audible alarm (not shown), generate a systems management alertto another computer, or generate a prompt at a screen, for detection bya staff person.

In the present example, the ultrasonic signal generated by thetransducer 16 is a 100 nanosecond (nsec.) pulse. The pulse travelsthrough the paper roll 10 resulting in a return echo. The return echoover time reveals the amount of paper (P) between the outer surface(outer diameter=D_(o)) and the inner carrier (inner diameter=D_(i)) ofthe paper roll 10, by multiplying the speed of sound (i.e., 1432 mm./ms.(millimeters per millisecond)) by the edge feature times. Edge featuretimes or Echos (E) are the times, in milliseconds, between particularedges of the reflected ultrasonic waveform. Thus:

P=(D _(o) ⁻ D _(i))/2=(Emm.)(1432 mm/ms)

The unit of P is mm.

Turning now to FIG. 2, a plot of a detected return echo from the paperroll 10 is shown for the 100 nsec. pulse ultrasonic signal. The firstportion of the plot, i.e., from 0 to 0.0014 ms. (=1.4 us), reveals anamount of paper at one side on the paper roll (P (between an outersurface of the paper roll 10 (outer diameter=D_(o)) and an ousidesurface of the carrier 40 (inner diameter=D_(i))) to be 2.0 mm. (0.0014ms. multiplied by 1432 mm./ms). Further, knowing the outside diameter ofthe carrier 40, which is in this example 22 mm. results in an outsidediameter of the paper roll 10 of 26 mm.

P=(D _(o) ⁻ D _(i))/2→D _(o)=2P+D _(i)

A description of a method of determining the thickness of the paper onthe roll follows. After determining a first paper roll diameter (asdescribed above) and printing several receipts that total 1.5 meters(i.e., the length of paper fed in a printer is easily determined), asecond ultrasonic pulse detects an echo after 0.0007 ms. Now the amountof paper on one side of the paper roll 10 is 1.0 mm. (i.e., 0.0007 ms.multiplied by 1432 mm./ms.) and the second outside diameter of the paperroll 10 is 24 mm. (i.e., 22 mm., the outside diameter of the carrier 40plus 2 times 1 mm. amount of paper). The thickness of one layer of thepaper can be calculated by dividing the cross sectional area of the rollbetween the first outer diameter (D_(o)=26 mm.) and the second innerdiameter (D_(i)=24 mm.) by the length of paper printed (L=1.5 meters)resulting in a paper thickness of 0.05 mm. Thus the equation forthickness (T) is:

T=(π(D _(o)/2)²⁻π(D _(i)/2)²)/L=(D _(o) ²⁻ D _(i)/4)π/L

An example of an actual calculation of T would be (((26 squared minus 24squared)/4) multiplied by 3.1416 divided by 1500 mm.).

In determining when to signal for replacement of the paper roll 10, oneexemplary approach would signal that the paper supply is low when thedesired remaining paper length is specified. To provide this signal, thedesired outside diameter of the paper roll 10 is calculated byrearranging the equation for paper thickness to solve for D_(o)=thefirst outer diameter:

From above: T=(D_(o) ²⁻D_(i) ²/4)π/L

→TL/π=(D _(o) ²⁻ D _(i) ²/4)→4TL/π=D _(o) ²⁻ D _(i) ²→4TL/π ⁺ D _(i) ²=D _(o) ²

→D _(o)=(4TL/π ⁺ D _(i) ²)^(1/2)

Thus the preceding calculation of D_(o) takes the square root of the sumof 4 times the thickness of the paper times the specified length dividedby 3.1416 and the outer diameter of the carrier 40 squared. Here thethickness of the paper can be determined by the method describedpreviously or it may be known.

The calculated outside diameter of the paper roll 10 less the knowninside diameter of the paper roll 10 (i.e., the outside diameter of thecarrier 40) divided by 2 yields the amount of paper that should be onone side of the paper roll 10 to signal that paper should be replaced.In other words, this is the minimum amount of paper (P) that theultrasonic must pass through without low paper being indicated.

P=(D _(o) ⁻ D _(i))/2

The corresponding echo time (E) is now calculated by dividing thisdistance (P) by 1432 mm./ms.: E=(P mm.)/1432 mm./ms. The unit of E isms.

For example: if the signal for replacement of the paper is desired tooccur when there are 5 meters of paper left on a carrier having a 22 mm.outer diameter and using the paper thickness calculated previously of0.05 mm, the desired outside diameter of the paper roll 10 is 28.3 mm.(i.e., square root of (4 times 0.05 mm. times 5000 mm. divided by 3.1416plus 22 mm. squared)). The desired amount of paper on the paper roll 10is 3.15 mm. (i.e., 28.3 minus 22 divided by 2) and the desired echo timeis 0.0022 ms. (i.e., 3.15 mm. divided by 1432 mm./ms.).

Once the outer diameter (D_(o)), the inner diameter (D_(i)) and paperthickness are known, the length of paper remaining on the paper roll (L)can be easily determined by rearranging the equation for paper thicknessto solve for L:

From above: T=(D_(o) ²⁻ D _(i) ²/4)π/L

→TL=(D _(o) ²⁻ D _(i) ²/4)π→L=(D _(o) ²⁼ D _(i) ²)π/4T

The capabilities of the present invention can be implemented insoftware, firmware, hardware or some combination thereof.

As one example, one or more aspects of the present invention can beincluded in an article of manufacture (e.g., one or more computerprogram products) having, for instance, computer usable media. The mediahas embodied therein, for instance, computer readable program code meansfor providing and facilitating the capabilities of the presentinvention. The article of manufacture can be included as a part of acomputer system or sold separately.

Additionally, at least one program storage device readable by a machine,tangibly embodying at least one program of instructions executable bythe machine to perform the capabilities of the present invention can beprovided.

There may be many variations to the steps (or operations) describedtherein without departing from the spirit of the invention. Forinstance, the steps may be performed in a differing order, or steps maybe added, deleted or modified. All of these variations are considered apart of the claimed invention.

While the preferred embodiment to the invention has been described, itwill be understood that those skilled in the art, both now and in thefuture, may make various improvements and enhancements which fall withinthe scope of the claims which follow. These claims should be construedto maintain the proper protection for the invention first described.

1. A system sensing paper on a paper roll, comprising: an ultrasonictransducer positioned to be in contact with the outer surface of thepaper roll; a transmitter circuit in communication with the ultrasonictransducer, the transmitter circuit providing a transmit signal to theultrasonic transducer, the ultrasonic transducer generating anultrasonic signal in response to the transmit signal, the ultrasonicsignal for transmission into the paper roll; a receiver circuit incommunication with the ultrasonic transducer, the receiver circuitproviding a received signal indicative of an ultrasonic return echo fromthe paper roll, the ultrasonic return echo resulting from the ultrasonicsignal interacting with the paper roll; and a processor circuit incommunication with the transmitter circuit and the receiver circuit, theprocessor circuit determining an amount of paper remaining on the paperroll in response to the transmit signal and the receive signal, theprocessor providing an output signal when the amount of paper remainingfalls below a threshold.
 2. The system of claim 1 further comprising: anindicator for indicating, in response to the output signal, that thepaper roll needs to be replaced.
 3. The system of claim 2 wherein theindicator comprises one of a visual display and an audible alarm.
 4. Thesystem of claim 1 further comprising: a holder receptive to theultrasonic transducer for biasing the ultrasonic transducer to be incontact with the outer surface of the paper roll.
 5. The system of claim1 wherein the ultrasonic signal has about a 100 nanosecond pulse width.6. The system of claim 1 wherein the processor determines the amount ofpaper remaining on the paper roll by multiplying the speed of sound byan edge feature time.
 7. The system of claim 6 wherein the processordetermines the length of paper remaining on the paper roll is determinedby:L=(D _(o) ²⁻ D _(i) ²)π/4T, where, L is is a length of paper remainingon the paper roll, D_(o) is an outer diameter of the paper roll 10,D_(i) is an inner diameter of the paper roll 10, wherein the innerdiameter of the paper roll 10 is equivalent to an outside diameter ofthe carrier, and T is the thickness of one layer of the paper on thepaper roll.
 8. The system of claim 1 wherein the ultrasonic transducercomprises a piezoelectric ceramic ultrasonic transducer.
 9. A method ofsensing paper on a paper roll, comprising: transmitting an ultrasonicsignal into a paper roll; detecting an ultrasonic return echo from thepaper roll, the ultrasonic return echo resulting from the ultrasonicsignal interacting with the paper roll; and determining an amount ofpaper remaining on the paper roll in response to the ultrasonic returnecho transmit signal.
 10. The method of claim 9 wherein the processordetermines length of paper remaining on the paper roll is determined by:L=(D _(o) ²⁻ D _(i) ²)π/4T, where, L is a length of paper remaining onthe paper roll, D_(o) is an outer diameter of the paper roll 10, D_(i)is an inner diameter of the paper roll 10, wherein the inner diameter ofthe paper roll 10 is equivalent to an outside diameter of the carrier,and T is a thickness of one layer of the paper on the paper roll. 11.The method of claim 9 further comprising: indicating, in response to thedetermining the amount of paper remaining on the paper roll, that thepaper roll needs to be replaced.
 12. The method of claim 9 wherein theultrasonic signal has about a 100 nanosecond pulse width.
 13. The methodof claim 9 wherein the determining the amount of paper remaining on thepaper roll comprises: multiplying the speed of sound by an edge featuretime.